The present invention relates to a pressure regulator device adapted to regulate the fuel pressure in a fuel circuit of an internal combustion engine supply system.
As is known these devices are designed to keep the fuel pressure substantially constant within the circuit and comprise a housing formed by a cup-shaped body and a bell-shaped cover which is secured to this body, a deformable membrane secured to the housing and defining, together with the body, a chamber for the fuel and a movable shutter member adapted to bring this chamber into communication with an outlet opening. The shutter member has a working surface arranged to bear on an appropriate seat so as to control the flow of the fuel through the outlet opening and also comprises a surface which bears on a corresponding surface of a plate connected to the deformable membrane and held against the shutter member by a spring.
When the fuel pressure within the chamber exceeds a predetermined value, a force is applied to the deformable membrane, which force is enough to overcome the elastic reaction of the spring so as to allow the separation of the working surface of the shutter member from its seat and, therefore, the discharge of a certain quantity of fuel through the outlet opening.
Regulator devices of the type described above have some drawbacks.
In the first instance, they are rather complex and therefore expensive because of the large number of components constituting them; in addition to the basic components listed above, others are needed for the satisfactory operation of the device; a sleeve inserted in an appropriate hole is normally secured in the cup-shaped body so that the fuel can be supplied within the chamber defined by this body; in addition, the seat on which the working surface of the shutter member bears is normally obtained on a ring of appropriate material which is connected to a bushing in which the outlet opening for the fuel is obtained and which is secured, for instance by welding, in an axial perforation in the body. Numerous components are also provided for the mechanical fastening of some components to others as well as members providing leak-tightness between the components.
Moreover, the sealing action which the shutter member of the device exerts, when in its closed position, is not always very efficient. This is due to the fact that the bearing between this shutter member and the plate secured to the deformable membrane is not very correct with the result that the resultant of the pressures exchanged between the plate and the shutter member does not coincide strictly with the axis of the shutter member itself; this is principally due to the fact that the above-mentioned surface of the plate on which the shutter member bears lacks precision, since it is obtained by conventional mechanical machining operations with the removal of material.